The present invention relates to an inspection to detect defects (short circuits and broken circuits) and foreign particles in patterns being inspected, and more specifically to a method of correcting a sensor output particularly when a one-dimensional or two-dimensional image sensor is used as a detector.
Conventional techniques associated with image sensor shading correction include: a method which, as disclosed in JP-A-2000-358160, moves a carriage to scan a text reading window, which is fixed at a home position, over a reference white plate and, based on the white reference position thus read, generates correction data; and a method which, as disclosed in JP-A-10-224529, sets a first mode that variably magnifies a read image by changing the scan speed of the line sensor, a second mode that variably magnifies a read image by a variable magnification circuit, and a third mode that performs both a variable magnification by changing the line sensor scan speed and a variable magnification by a variable magnification circuit, and adaptively selects one of the modes according to a size of an original and a reading resolution.